The present invention relates to mobile communications systems such as cellular telephone systems and, more specifically, to a system for reducing power consumption in a mobile or portable transceiver of such a system.
In many communications systems, the transceivers are only sporadically active. For example, a cellular telephone remains idle for significant periods of time when no call is in progress. During such idle periods the cellular telephone consumes substantially the same amount of power as during active periods. However, to ensure that a transceiver receives sporadically transmitted messages, it must continuously monitor a channel. In a digital cellular telephone system, such as that described in U.S. Pat. No. 5,056,031 entitled "Method and Apparatus for Controlling Transmission Power in a CDMA Cellular Telephone System" and copending U.S. patent application Ser. No. 07/543,496 entitled "System and Method for Generating Signal Waveforms in a CDMA Cellular Telephone System," both assigned to the assignee of the present invention, messages transmitted by a base station may include those for alerting the mobile station to the presence of an incoming call and those for periodically updating system parameters in the mobile station.
While a mobile station installed in a vehicle may be powered by the vehicle's electrical system, prolonged use of the mobile station when the vehicle is not operating may drain the vehicle's battery. Furthermore, many mobile stations are portable and powered by an internal battery. Personal Communications Systems (PCS) handsets are almost exclusively battery powered. In any such stations it is desirable to minimize power consumption to increase battery life.
A mobile station may consume significant amounts of power by continuously monitoring the channel for incoming messages. The resulting power drain on the battery reduces the time available for actively handling calls. A system that reduces power consumption by periodically monitoring the channel for incoming messages during idle periods would be highly desirable. These problems and deficiencies are dearly felt in the art and are solved by the present invention in the manner described below.